Trivić S, Leskovac V, Zeremski J, Stancić B, Anderson B M
Faculty of Science Novi Sad, Yugoslavia.
J Enzyme Inhib. 1998 Feb;13(1):57-68. doi: 10.3109/14756369809035827.
Acetaldehyde, propionaldehyde, glyceraldehyde-3-P and 4-dimethylaminocinnamaldehyde form Schiff bases in Tris. HCl buffers; the rates of formation and dissociation of Schiff bases, and equilibrium constants for their formation are very similar for the first three aldehydes. The steady-state kinetic constants for the yeast alcohol dehydrogenase-catalyzed reaction, propan-1-ol + NAD+ reversible propionaldehyde + NADH + H+, have been determined in several Tris. HCl buffers of increasing concentration at pH 8.1. In the forward direction, oxidation of alcohol, most kinetic constants are increased by increasing concentrations of Tris. In the reverse direction, reduction of aldehyde, substrate, NADH, Tris and Schiff base were equilibrated before enzyme reaction was started. It was found that Schiff base, rather than Tris, binds to free enzyme competitively with respect to NADH. Tris and Schiff base do not influence the binding of aldehyde to enzyme in any way.
乙醛、丙醛、3-磷酸甘油醛和4-二甲基氨基肉桂醛在Tris·HCl缓冲液中形成席夫碱；前三种醛形成席夫碱的速率和解离速率以及形成席夫碱的平衡常数非常相似。在pH 8.1时，已在几种浓度不断增加的Tris·HCl缓冲液中测定了酵母乙醇脱氢酶催化的反应（丙醇+NAD⁺⇌丙醛+NADH+H⁺）的稳态动力学常数。在正向反应中，即醇的氧化反应中，大多数动力学常数会随着Tris浓度的增加而增大。在逆向反应中，即醛的还原反应中，在酶反应开始前使底物、NADH、Tris和席夫碱达到平衡。结果发现，席夫碱而非Tris与游离酶结合，相对于NADH具有竞争性。Tris和席夫碱对醛与酶的结合没有任何影响。
